The use of carbon--carbon (C--C) composites as a dry friction material is well known in the aerospace industry. The majority of military and commercial aircraft which have been designed over the past 20 years have used C--C brake friction materials. U.S. Pat. No. 3,897,582, issued to Olcott, and U.S. Pat. No. 3,991,248, issued to Bauer, provide examples of the Chemical Vapor Deposition (CVD) processes used to fabricate C--C materials.
The maintenance of frictional properties while under extreme thermal loading and other advantages of the C--C composites have been recognized by the automobile racing community. U.S. Pat. No. 4,846,326, issued to Tilton et al, describes the use of C--C materials as high performance clutches.
Pyrolytic carbon material, e.g., pyrolytic carbon/fiber composites formed using pyrolytic carbon deposited on carbon fibers work well for wet friction applications. U.S. Pat. No. 4,291,794, issued to Bauer, U.S. Pat. No. 4,700,823, issued to Winckler, U.S. Pat. Nos. 4,844,218 and 5,033,596, issued to Genise, describe these openly porous carbonaceous materials and their use in wet friction devices. These materials are described as low density C--C composites, (e.g., 0.9-1.2 g/cc), made by the deposition of pyrolytic carbon on carbon fibers.